Mesure du volume d'air expiré.

1. General Description

The Harvard Dry Gas Meter is a positive-displacement volumetric measuring device used to accurately quantify the volume of expired or collected gases (e.g., via Douglas bags). It is widely used in respiratory physiology and energy metabolism laboratories.

 

2. Components and Design

Device body: Robust, equipped with an internal membrane (diaphragm) that moves proportionally to the gas volume.

Connections: Inlets and outlets adapted for standard tubing (22 mm and 30 mm).

Digital display (LED): 4-digit screen, displays in 0.1 L increments, range from 0.1 to 999.9 L, featuring a RESET button for zeroing.

Pulse output (TTL): Generates a 5V pulse for every 0.1 L measured, enabling connection to a data acquisition system.

 

3. Performance

Accuracy: Approx. ±1.5%.

Measurement Range: 0.1 L up to 999.9 L.

Operating Principle: Volumetric measurement by positive displacement of the diaphragm.

 

4. Power Supply

9V battery (included) for standalone operation.

5V Micro-USB port for external power and charging.

 

5. Dimensions and Weight

Dimensions: approx. 20 × 22 × 37 cm.

Weight: approx. 4.05 kg.

 

6. Additional Features

Display with adjustable contrast.

LED indicator showing battery charge status.

Compatibility with gas collection and analysis systems (Douglas Bag, metabolic carts).

 

7. Advantages and Limitations

 

Advantages:

  • Accurate gas volume measurement.
  • Simple and robust usage.
  • Easy integration with collection and data acquisition systems.

 

Limitations:

  • Does not provide direct analysis of O₂ or CO₂ concentrations (measures volume only).
  • Accuracy can be affected by potential leaks or significant flow variations.
  • Requires regular maintenance (diaphragm, valves).